A conventional ceiling fan includes a suspension part fixed to a ceiling, a pipe suspended from the suspension part, and a main body fastened to the pipe, and the pipe is fastened to the main body with a coupling bolt and a nut.
In an example, a lower surface of a head of the coupling bolt is a curved surface that conforms to an outer surface of the pipe and has a circular arc-shaped cross section (refer to, for example, PTL 1).
When fastening using such a conventional coupling bolt, only the nut needs to be rotated without fixing the coupling bolt, which is excellent in operability. However, when the coupling bolt is inserted at a wrong angle, the coupling bolt is fixed in the state where the circular arc-shaped curve surface does not conform to the outer surface of the pipe. As a result, coupling between the pipe and the main body is disadvantageously loosened during operation of the ceiling fan.